The application of single photon emission computed tomography (SPECT) technique in molecular imaging is becoming more and more popular, as it can be performed without requiring any accelerator and also it can produce required images in an instant manner, due to the radioisotope that is commonly used by SPECT imaging has a comparatively longer half-life period. Recently, SEPCT scanner is becoming the essential instrument for many animal studies relating to internal orgasm whichever requires sharp images with very accurate spatial and contrast resolutions.
Conventionally, the animal SPECT scanner is generally configured with pinhole collimator, which is made of a material of high atomic number and high density based on the fact that beams of radiation are better absorbed by materials with high atomic number and high density. Therefore, SPECT scanner using pinhole collimator can be very expensive, not to mention that it can be very difficult to manufacture. In addition, in order to acquire SPECT images, either the pinhole collimator and the detector of the SPECT scanner are rotated around an object to be scanned in a circular orbit or the scanned object is enabled to rotate with respect to the pinhole collimator and the detector, and thereby, projections are acquired at defined points during the rotation, typically every 3-6 degrees. In most cases, a full 360-degree rotation is used to obtain an optimal reconstruction. However, in a situation when the pinhole collimator is enabled to rotate about the scanned object in a circular orbit for acquiring projections, it is more than often that there are ghost artifacts appeared on the recontruction image due to certain mechanical assembly inaccurqacy as the pinhole collimator can be very heavy.
There are already many studies available for reducing the aforesaid image noises that are generated due to poorly calibrated pinhole collimator in orbital movement. One of which is a SPECT system based on a static triangular detector setup, with a tungsten cylindric imaging cavity in the center and 75 gold micropinhole apertures in the cavity wall. The pinholes that are evenly distributed into multiple rings on the cavity wall are focused on the center of an interested field-of-view (FOV) where the scanned object is disposed. Operationally, detectors are orientated for acquiring gamma rays that travel passing through the pinholes so as to be used in SPECT image reconstruction. As the pinhole collimator is built like a cylindric imaging cavity, the scanned object can be placed inside the cylindric pinhole collimator while allowing the pinholes that are formed on the cavity wall to be arranged surrounding the scanned object. Thereby, to acquire SPEACT images, neither the scanned object nor the pinhole collimator and detectors are being driven to rotate in any way, and also the aforesaid SPECT system is able to obtain 75 non-overlapping projections in one shot and used for reconstructing high resolution images. However, since each pinhole on the cylindric pinhole collimator is a micro aperature that is formed with a width smaller than 1 millimeter, such cylindric pinhole collimator can be very expensive and difficult to build.
Therefore, it is in need of a low-cost, easy-to-build, high-resolution SPECT scanner and the operating method thereof.